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When your CNC router skips steps or your 3D printer loses position mid-print, the culprit is often a mismatched or worn timing pulley. Engineers, makers, and automation builders who demand repeatable, slip-free motion need a timing pulley that holds tight tolerances across every tooth. This L-type synchronous timing pulley is designed for hobbyists and professionals who cannot afford positional drift in their drive systems.
Each pulley is machined from aluminum alloy with a natural silver finish and features a 27 mm (1.06 in) tooth width engineered to pair with standard 25 mm wide L-type synchronous belts. Tooth counts span 10T to 40T, and bore diameters range from 6 mm to 28 mm (0.24 in – 1.10 in), covering the most common shaft sizes used in desktop CNC machines, 3D printers, and light industrial automation.
Typical applications include CNC router X/Y axis drives requiring low-backlash synchronous motion, FDM 3D printer extruder and gantry systems, and tabletop robotic arm joints where precise angular positioning is critical. The L-pitch (9.525 mm / 0.375 in) tooth profile distributes load evenly across multiple teeth, reducing wear and extending service life in continuous-duty cycles.
| Belt Type | L-Type Synchronous (3/8" pitch) |
|---|---|
| Pitch | 9.525 mm (0.375 in) |
| Tooth Count | 10T, 12T, 14T, 15T, 16T, 17T, 18T, 19T, 20T, 22T, 24T, 25T, 26T, 28T, 30T, 32T, 33T, 40T |
| Tooth Width | 27 mm (1.06 in) |
| Compatible Belt Width | 25 mm (1 in) |
| Bore Diameter | 6 mm, 6.35 mm, 8 mm, 10 mm, 12 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 22 mm, 24 mm, 25 mm, 28 mm, 30 mm |
| Material | Aluminum Alloy |
| Finish | Natural / Silver Anodized |
| Bore Retention | Set-Screw |
| Outer Diameter | See variant options |
| Flange Diameter | See variant options |
| Hub Length | See variant options |
| Weight | See variant options |
The tooth count determines your drive ratio. Divide the driven pulley tooth count by the driving pulley tooth count to get the ratio. For example, a 20T driving pulley paired with a 40T driven pulley gives a 2:1 reduction. For CNC and 3D printer gantries, matching tooth counts on both ends (1:1) is common for direct-drive linear motion.
Measure your motor shaft diameter with a caliper before ordering. Common NEMA 17 stepper motors use a 5 mm shaft — note that 5 mm is not listed; the closest available bore is 6 mm, which would require a 6 mm shaft or a sleeve adapter. NEMA 23 motors typically use 6.35 mm (1/4") or 8 mm shafts, both of which are available in this listing. Always confirm your shaft diameter before selecting a variant.
No. This pulley uses the L-type (trapezoidal) tooth profile with a 9.525 mm pitch. HTD and GT2 belts use a different curvilinear tooth profile and are not interchangeable. Ensure your belt is specifically an L-type (3/8" pitch) synchronous belt with 25 mm width for correct engagement.
Aluminum alloy pulleys are well-suited for light to medium-duty continuous operation such as CNC routing, 3D printing, and small robotic systems. For heavy industrial applications with sustained high torque or abrasive environments, a steel pulley may be more appropriate. The aluminum construction keeps rotational inertia low, which benefits servo and stepper motor response times.
Each pulley includes a set-screw bore. Tighten the set screw against a flat on the motor shaft (if present) or directly against a round shaft using the appropriate hex key. For critical applications, apply a small amount of thread-locking compound to the set screw and ensure the shaft surface is clean and free of oil before assembly.
Yes. L-type pulleys are commonly used in larger-format 3D printers and CNC machines where the wider 25 mm belt provides higher torque capacity than the narrower GT2 6 mm belts used in compact printers. Select the tooth count that matches your existing belt loop length and the bore size that fits your motor shaft.
The 6 mm bore is sized for metric shafts (common in Asian-standard motors and hardware), while the 6.35 mm bore corresponds to 1/4 inch — the standard for many North American and European motors and gearboxes. Using the wrong bore will result in either a loose fit or an inability to install the pulley. Measure your shaft carefully and select the matching bore.
